1. Field of the Invention
This invention relates generally to a bale-binding machine that uses a narrow head wire feeder for looping and fastening wire around a bale of bulk material such as cotton.
2. Related Art
Wire baling of bulk materials benefits from increased speed and reduced materials cost through automation. Bulk materials include fibrous bulk materials such as cotton and nylon. Fibrous materials are commonly formed into bales by simultaneous compression and binding. There is a continuing need in the automated baling art to improve the efficiency, reliability and accuracy of the bale binding process.
Baling wire performance requirements vary depending upon the bulk material being baled. Such requirements range from industry standard specifications to general operational parameters, such as minimum speeds required for profitability. The Cotton Council issues standards specifying particular lengths of wire around various sizes of bales and the tension that the wires must withstand. These standards vary for different bale configurations such as a “standard density,” bale or “universal density” bale. The most common bale configuration is “standard density,” which is 20×54 inches in size, for which Cotton Council Industry Standards require six baling wires which are 9¼ inches apart from one another.
Current automated baling machines use an articulated track to guide wire around bales of bulk material, such as cotton, while that bale is under compression. Part of the wire guide track in current automated balers must be removable to a second position after the ends of the baling wire have been tied together, in order to allow ejection of the bale and insertion into the baler of the next unit of material for baling. Material to be baled is typically introduced into the automatic baler under vertical compression. Typical pressures for an industry standard 500 pound, 20×54 inch cotton bale are in excess of 300 tons. Horizontal plates called follower blocks apply compression through platens which contact the surface of the cotton or other material being compressed. The Platens incorporate slots which run lateral to the longitudinal axis of the bale. There are six slots in the platens. These slots allow the baling wire to be wrapped around the bale while it is still under compression. Under the lateral slots are lateral channels for insertion of the wire guide tracks in both the upper and lower platens in automatic balers.
Automatic baling machines use power drives to propel the wire around the bulk material to be baled through the wire guide tracks. Typical wire propulsion speeds are about ten feet per second. This propulsion is conventionally imparted to the baling wire by means of drive wheels. Prior art automatic balers powered the drive wheels hydraulically. Prior art automatic balers have been able to align six or even eight assemblies of wire feeders, guide tracks and knotters abreast, see U.S. Pat. No. 4,450,763 patent column 8, lines 61-64. Also see U.S. Pat. No. 5,379,687, to Moseley disclosing six wire feed/guide track assemblies abreast, see column 4, lines 61-62. However, these were driven with a single drive shaft rotated by a chain connected to an hydraulic motor, column 7, line 66 through column 8, line 7.
Hydraulic drive created leakage problems. Hydraulic leaks are highly consequential in fibrous bulk material baling because cotton or nylon stained with hydraulic fluid is unmarketable. Leaks of hydraulic fluid onto components that come in contact with the cotton will stain not only the first bale, but subsequent bales of fibrous material as well. Lost time for repair of hydraulic leaks is problematic because baling operations such as cotton gins are subject to time constraints due to the seasonal nature of cotton harvesting and because unattended bulk cotton waiting for baling can be ruined by fermentation if not baled and distributed in a timely fashion. A potential solution to such problems is powering the drive wheels with electric motors. Feeding wire and/or twisting knots with electric motors is known in the prior art, see U.S. Pat. No. 4,450,763 to Saylor, column 9, lines 36-38 and column 10, lines 41-44.
Automatic baling machines using either simple electric motors or hydraulic drive operated with a certain degree of inefficiency. In order to loop baling wire around bulk material to be baled, then release the wire from a guide track and finally knot the ends of the wire, tension had to be generated on the wire during baling. Likewise, in order to properly knot the ends of the wire, tension had to be maintained in the twisting procedure that generates the knot. These tensions must be maintained within prescribed ranges to optimize efficiency and to produce a final bale that complies with industry standards. Certain knotting speeds must be avoided because too much speed in the twisting procedure produces brittleness, metal fatigue and weak knots, see U.S. Pat. No. 4,450,763, Column 1, lines 59-65. Weak knots fail industry standards. Too much tension in the overall wire loop can generate weaknesses or wear-points in the baling wire, or can generate wear in the wire guide tracks or other parts of the automatic baling machine. Automatic baling machines would benefit from more precise control of such variables. Further, if the position of the leading and trailing ends of the wire were precisely controlled, costs could be reduced by using less wire. If precise control guaranteed compliance with industry strength standards, less costly gauges of wire could be used. Electric and hydraulic drive systems required large margins of error for tension, position, torques and speeds in order to ensure compliance with industry standards and to avoid breakdowns. Large margins of error in turn require heavier gauges of wire, which are more expensive. Electro servo motors increase precision in these areas, and thereby narrow acceptable margins of error.
In analogous baling operations, such as baling hay, the recognition of the advantages of more precise control has lead to the use of electric servo motors, capable of outputting data which may be used for precise control of position, torque and speed. U.S. Pat. No. 5,746,120 to Jonsson illustrates the use of electric servo motors in balers. However, bulky electric servo motors have only been used in the prior art in configurations having only one wire loop, see U.S. Pat. No. 5,746,120.
Prior art automatic baling machines oriented drive wheels on the same plane as the bale wire loop around the bale. See, U.S. Pat. No. 5,746,120 at column 2, line 67, FIG. 3; U.S. Pat. No. 4,450,763, Column 7, line 50, 65 and Column 8, line 9; U.S. Pat. No. 5,379,687, Column 8, line 4-6. This configuration necessitates that the drive wheel axis and the driving electric servo motor be oriented perpendicular to the plane of the bale wire loop. Such an orientation is problematic in that the drive wheel/drive servo motor assembly would occupy more than the 9¼ inch wide space which is the Industry Standard for bale wire loop spacing. Accordingly, prior art automatic bale machines were not capable of aligning six sets of electro-servo motors, drive wheels and wire guide tracks in parallel within the 9¼ inch industry standard space limitations. Consequently, looping and tying all six bale wires simultaneously was impossible.
Prior art automatic balers addressed this issue by configuring three or fewer sets of electro-servo motors, drive wheels and bale wire guide tracks in parallel. The present applicant has mounted three on a carriage that would tie a first set of three bale wires 18 and ½ inches apart at a first position, and then the carriage would translate down a boom to a second position 9¼ inches offset from the first position and repeat the bale wire loop and tie procedure for the second set of three bale wire loops interspersed between the first three loops.
Typical execution times for the two-step prior art procedure include double the looping and tying time which, in addition to the translation time, yields a total baling time for each bale of 16 to 20 seconds. If six wires could be looped and tied simultaneously, execution times for one step baling would be four to five seconds.
There is a need in the art to minimize execution time for looping and tying six bale wires, while maintaining operational reliability and efficiency, and improving precision and efficiency.